Hot Corrosion Degradation of Marine Gas Turbine Materials Subject to Mixed-Mode Thermal Exposures and Complex Corrosion Environments
Abstract
Gas turbine engines are used throughout the Naval fleet as aircraft and ship propulsion and power systems. The materials utilized in the hot-section of the turbines are subjected to high temperature corrosive conditions associated with the salt laden environment inherent with the maritime operational theater. Previous and ongoing research has demonstrated that the performance and lifetime of t"urbine hot-section materials is highly dependent upon the exposure temperatures, thermal cycling history, mechanical stress inherent"" in the engine operation, and the unique, corrosive Naval environment. Ensuring the durability and reliability of new high temperatu""re propulsion system materials is critical for enabling system improvements and redesigns for improved efficiency, while also reduci"ng the total ownership cost (TOC). Extensive research is underway to develop both the next-generation materials sets and the fabrication techniques that will enable these improvements. While extensive research has been done to understand the accelerated degradat"ion of hot section materials exposed to sulfates resulting from the ingestion of sea-water and the combustion of sulfur-laden fuel,"" and the basic underlying mechanisms controlling degradation rates are fairly well understood, our understanding of the roles of (1)"" microstructuralheterogeneities and chemical partitioning, and (2) ingestion of atmospheric particulate matter, and (3) widely vary"ing service environments (mixed/cyclic exposures to corrosion and oxidation conditions) is lacking. We propose to study the response of turbine hot-section materials to complex exposure environments representative of emerging Navy turbine propulsions systems and o"perational protocols, and establish a mechanisms-based understanding of the material system responses. A key objective is to capture"" materials response under representative exposure conditions. The complex nature of the intake air composition, dynamic combustion e""nvironment, fuel composition, and thermal conditions make it difficult to ensure that laboratory tests are developed in a manner to" accurately capture realistic materials response that can be correlated directly with field observations. The overall goal of the" proposed effort is to establish a mechanisms-based understanding of the synergistic role of mixed-mode (Type II, Type I and oxidati""on condition) exposures and the inclusion of additional species (CMAS constituents as both oxides and sulfates, potassium, Fe, etc.)"" in the corrosive deposit chemistries. The research will integrate burner-rig and furnace based materials exposures, electrochemical"" testing of corrosion environments, high resolution microscopy and microanalysis to quantify degradation processes, microstructural"" evolution, and the role partitioned alloy chemistry and microstructure, and computational thermodynamics assessments to understand" the mechanisms and kinetics of the active hot-corrosion mechanisms. Providing an improved foundational understanding of observed degradation processes is essential for enabling the design of materials capable of being utilized in increasingly hostile Naval environments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 07, 2017
- Source ID
- N000141712696
Entities
People
- Daniel Mumm
Organizations
- Naval Information Warfare Center Pacific
- Office of Naval Research
- United States Navy